I've recently bought a LinkStation HD-120HLAN (120gb) and managed to install a telnetd, ftpd and also gcc. Once you read thru these japanese sites with http://babelfish.altavista.com you figure out that it's pretty easy.
Unfortunately, I haven't found a way to open the LinkStation box without breaking some parts, but I don't care at all now that I have a small and silent Linux box 
After connecting the internal 120gb harddisk thru an external USB 2.0 harddisk kit, I made a backup of the first partition with "dd". Then I ran "fix_ext2_magic" from http://bonner.s45.xrea.com/ . After this I was able to mount the first partition easily.
You can download a precompiled telnetd and ftpd from the site mentioned above ("linuxbox-1.0.ppc.tar.gz"). Just install it and don't forget to edit the root password so that you can login later.
Reconnect the harddisk to the LinkStation and there you go. It's absolutely stunning! A great little box with so many features and now I can even login and compile whatever I want 
Cheers
ole at mobileways.de